Whipstock



March 13, 1951 R. BUTTOLPH WHIPSTOCK Filed Nov. 14, 1946 Ralph Buol hINVENTo bore.

Patented Mar. 13, 1951 UNITED STATES PATENT OFFICE'.

' Y 2,544,982V Y t WHIPSTO'CK Ralph Buttolph, Long Beach, Calif.,assignor /to Eastman Oil Well Survey Company, Denver, Colo., acorporation of Delaware Application November 14, 1946,v SerialNo.'709,711

This invention relates to new and useful iin-,- provements inwhipstocks. This application is led .as a continuation-in-part ofapplication Serial No. 535,235, now abandoned, in which I am aco-inventor.

One object of the invention is to provide an improved whipstock of --theremovable type, such as is illustrated in the patent to McVicar No.1,970,761, the invention being an improvement on the device disclosed insuch patent.

`In the usual removable whipstock, as exempli- Z'ed by McVicar, whereinthe drill bit is utilized '-to withdraw the whipstock from the wellvbore, 'the drill blt c'o-acts with a collar at the upper end of thewhipstock body whereby'vsaid whipstock may be raised and lowered bymeans of said bit. The whipstock body is generally arcuate in Icrosssection with a' longitudinal inclined guide surface. The outer surfaceof the body is `disposed on a radius which iswswung from the longiAtudinal center of the body whereby said outer surface is substantiallyconcentric with the well bore into which it is lowered. Because .thisouter surface of the whipstock body is of the-.same radius throughoutits length and also because said body is of considerable length it isimpossible to lower a full gauge whipstock, that is a whipstock of thesame size as the well bo-re, into said As is well known a well bore hasirregularities thereinl and a whipstock having considerable length ofth'e" same size as said bore will not pass such irregularities andtherefore, cannot be lowered therethrough. For this reason.itis'neces'sary to employ a whipstock which is smaller` than the wellbore in order to assure lowering of thesazne into proper position. The

aisle of a whipstock smaller than the well bore causes the use of anundersize o-r smaller bit which means that the oiset bore drilled by thebity is less than the diameter ofthe main well bore.

In such instance, a reaming operation lmust be performed after theoifset bore has been started y 'ing the advantage of being capable ofdrilling a substantially full-gauge offset bore, whereby the.

usual reamingl operation in said offset bore is eliminated. 1 V'Animportant object of thisinvention is to provide an improved removableAwhipstockwhich j is solconstructed that a large bit only slightlyV less5- claims. (c1. c55-1.6)

than the-main well bore diameter, may be combined therewith, whereby theoffset bore which is drilled by said bit is substantially full-gauge,that is,r said offset bore Ais of substantially the same .diameter asthe main well bore in which the whipface maintained at a fixed distancefrom the lon- .gitudinalcenter ofthe whipstock; this construction makingit possible to lower the whipstock into a well bore having adiameter ofsubstantially the same size aslsaid whipstock, whereby a substantiallyfull-gauge bit may be employed in .drilling oi of said whipstock.

lA particular object ofthe invention is to rprovide an improvedwhipstock having its body portic-n substantially arcuate orsemi-circular in Avcross-section and having the center of the radius ofthe outer curved surface of said whipstock graduallychanged in alongitudinal plane from the upper to the lower end of said whipstock,

.whereby the outer curved surface cf said whipstock is progressivelyspaced a greater distance from thetrue longitudinal center'of the toolto'- ward its lower end; this construction permitting the whipstocktopass downwardly through 'a bore of substantially the same diameteras thedrill bit carried by said whipstock and at the same time permitting thewhipstock tc function iefficiently during the .fdrilling olf operation.

A further object of the invention is to provide an limproved whipstock,of the character described, having the opening for accommodating thedrill bit of such contour that any type of drill biteither adrag-or rockbit, may be combined with the whipstock.

The construction designed to carry out thevin.- vention willAf behereinafter described together with other features of the invention. Theinvention will be more readily understood from a reading of thefollowing specification and "by reference to the accompanying drawing,

wherein an example of the invention is shown.

Figure l is an elevation of a whipstock con- :structed in accordancewith the invention and illustrating :the drill bit in an. attachedposition, y Figure. 2 is j a transverse, vertical,l sectional viewshowing the whipstock in its set position and the drill bit detachedfrom said whipstock. y Figure 3 is an enlarged, horizontal,cross-sectional view taken on the line 3-3 of Figure l,

Figure 4 is an enlarged, horizontal, cross-sectional View taken on theline 4 4 of Figure l,

Figure 5 is an enlarged, horizontal, cross-sectional view taken on theline 5-5 of Figure 1 Figure 6 is an enlarged, horizontal,cross-sectional view taken on the line 6 6 of Figure l, and

Figure '7 is an enlarged, horizontal, cross-sectional view taken on theline 1--1 of Figure 1.

In the drawings, the letter A designates a whipstock including anelongate body portion I0 which is generally arcuate in cross-section andwhich will be hereinafter described in detail. A collar II is preferablyformed integral with the upper end of the whipstock body and the bore oropeni tegral with its upper end.

whipstock body A is so constructed that the drill bit used with thewhipstock drills a substantially full gauge hole. By means of thepresent invention a whipstock of substantially the same size as the Wellbore, so far as the operating function of said whipstock is concerned,may be lowered into the well bore and will readily pass through saidbore to the desired position at which it is to be set. Thus, thedisadvantage of having to employ an under size whipstock andconsequently an under size drill bit in a particular size-bore iseliminated.

The whipstock body A is elongate and as has been stated hasthe recoverycollar II made in- Immediately below the collar, the whipstock has astraight wall secjtion l1, arcuate in cross-section, with the ining I2through uns @011er is offset from. the een Y ter of said collar, as isclearly shown in Figure 3. A drill blt' I3 Which is attached'to a. SubI4 y is disposed below the collar and has a portion thereof iittingwithin the arcuate upper portion of the whipstock body. The drill bit islarger than the opening through the collar so that it cannot passtherethrough with the result. that the whipstock A may be suspended fromthe bit. The subl I4 is coupled to the lower end of a drill pipe I5 andhas an outer diameter which permits the sub to extend through theopening I2 of the collar II. A shear pin I6 Aconnects the 4sub to thecollar and with thisarrangement the whipstock may be lowered into thewell bore B by means of the drill pipe. Shearing of the pin I6 after thewhipstock A is set permits the drill bit and pipe to be moved downwardlyrelative to said whipstock, whereby the drill bit Will be guidedoutwardly by the whipstock body to'drill an offset or inclined bore.

gether with the offsetting of the bore I2 in' the collar I i. Ordinarilyin the usual whipstock, such as shown in the patent to McVicar No.1,970,761,

it has been the practice to construct the whipstock body with the outersurface of the whipstock body curved on a radius having its centeraligned with the longitudinal center-of said body. 'With sucharrangement the whipstock has its outer surface substantially concentricto the wall of the well bore into which it is lowered. Because of thisconcentricity between the outer-surfaceof the body of the whipstock` andthefwell'bore, it is necessary that the whipstock be under-gauge orsmaller than the well bore before it is possibe to lower the whipstocktherethrough. This is caused by the fact that the whipstock body has -aconsiderable length and the well bore isirregular which factors combineto make it impossible to lower a full-gauge Whipstock therethrough;there must be some clearance between v the outer surface of thewhipstock body and the inner wall of the well bore and this clearancehas l.,

been obtained by employing the under'size'whip- "j stock. Manifestly,the use of 'a reduced size whip- "stock requires that a small bit beusedso-that :subsequent reaming operations are necessary- YSince thedrill bit I3 is. 'larger than the opening I2 in the collar it is apnerwall I8 of this section being substantially parallel in a vertical planeto the outer surface of the Whipstock. When the drill bit is connectedto the whipstockffFigure l), a portion of said bit. engages the straightwall section. It is noted that the section I1 may be made relativelythin sothat this section together Ywiththe bit diameter is equal to thediameter of the well bore. Therefore, the bit` I-3 isv substantiallyfull gauge being less than the diameter of the well bore B only by theAthickness of the wall section II` Below the section Il, the whipstockbody is formed with an inclined guide' face I9 which is concave andwhich merges into the lower end of the straight sectionV I'I. In orderto obtain ,eifective drilling and desired angle, the radius R of theconcave guide face I9 which is engaged by the drill bit must remainconstant from its upper end to its lower end; thel inclined guidesurface is, of course, disposed at the desired angle -which varies apredetermined number of degrees per foot of length, The radius R of theconcave guide face i9 is in accordance with the particular diameter bitwhich is. employed since the purpose of this face isA to provide apartial seat for the bit as it moves downwardly of the whipstook. Sincethe face I9 is on a gradual inclination extending from its upper andlower end and since the radius R remains constant, the shiftingv of thecenter point of the radius R along the line L, as illustrated inFigures, 4 to '1, is in accordance with the degree of inclination of theface I9.'- In other Words, an imaginary line drawn through all of thecenter points of the radii R .extends` parallel to the inclination ofthe face I9vas shown in Figure 2.

By providing the inclined guide face, which increases the thickness ofthe whipstock body at its central portion from itsf upper to its lowerend, the bit is moved radially outwardlyvof the main well bore as saidbit is lowered longitudinally 0f the whipstock andthus, the bit isforced outwardly into the' formation at one side of the main well boreto drill an inclined bore at a desired angle with respect' to said mainbore B. Thev construction and' function of the concave guide face I9 isusual in all whipstocks.

To hold the guide face against displacement when the drilling operationcommences, the outer .wall or trailing side 20 of the whipstock mustengage the well bore Wall. As has been stated, according to priorpractice this outer wall 20 of the'whipstockrhas been made concentric tothe wall of the well bore, said outer wall being formed on a constantlradius throughout the entire length of the whipstock body. Theconstruction .of the bodywith its outer surface onra constant-Incarrying out-the 'presen-tiinventiorhitheesradiuswillpreventAthe-whipstockfromA entering a bore' having that same radius because asex-` outer surface constructed along Va radius which gradually andprogressively diminishes or is reduced toward its lower end. However,although naar the radius of the outer surface of the body progressivelychanges the outer longitudinal central portion of said surface,indicated by the letter Din Figures 4 to 7, is spaced a constantdistance from the longitudinal center, indicated at C, of the whipstockbody throughout the length of the body. Referring to Figure 4, the outersurface of the upper end of the whipstock body is formed o n-the radiusRI being swung on the longitudinal center C of the body. At thehorizontal line 5 of Figure l, the radius of thev outer surface of thebody has been reduced to the radius R2 shown in Figure 5 with thereduction in radius being effected by spacing the center C2 of theradius R2 from the longitudinal center C of the whipstock body. Thespacing of the center C2 from the center C is in a longitudinal plane Lwhich extends through the center C and the central portion D of theouter surface of the body and thus `the distance between the centralportion D and the longitudinal center C remains constant even though theradius of the outer surface has been diminished. The change in radius ofthe outersurface of the whipstocl: body from the radius Rl to R2 isgradual or progressive so that it is' understood that the radii of theouter sur-I face of the whipstock between the horizontal lines 4 4 and 55 of Figure l are progressively less with the center points of suchradii being disposed between the longitudinal center C of theV centerlpoint C2 ofFigure 5. 4The area of the outer surface ofv the whipstockbetween the lines 5 5 and 6 5 of Figure l is formed on radii which aregradually reduced from the radius'R2 to the radius R3 and have theircenter points in the longitudinal plane L between the centerpoint C2 andC3.r

In Figure 7, the further reduction in radius is illustrated Aat the linef l' of Figure i. The radius R4 at this point is less than the radius R3and is swung on a. center C4 which is located in the longitudinal planeL but spaced from the center C3. The area of the cutersurface of thewhipstock between the lines -S and' 'E 'i is on diminishing radii havingtheir centers disposed between thecenter points C3 and C4. Below thehorizontal plane 1 1, the radius of the outer surface of the whipstockcontinues to reduce in the same manner as above with the center pointsoi' theY progressively diminishing radii always remaining `in thelongitudinal plane L and each 'oeing spaced slightly closer to thecentral portion D of the outer surface, whereby the distance between theportion D and the center C of the whipstock body remains constantthroughout the length of the whipstock.

As'the outer surface of the whipstock body is eKTA gradually andprogressively reduced and since distance between the central portion ofthe outer'f surfaceand the center C is maintained constant;

clearance or by-pass areas E are formed between the sides or remainderof the outer surface of the whipstock body and the well bore.

It is noted that the radius RI,

wall of the well bore at the horizontal plane 4 4 of Figure 1; from theplane, the radius of the outer surface progressively decreases to thelower end of the body as above explained and the amount of decrease in'radius maybe varied tof obtain the desired size by-pass area E'. Theflsmallest radius is, of course, -at the extreme lower end of the body andits center is determined be-'' cause it is swung from the centralportionD of the whipstock body. Thus, after the size ofthe from thecenter point of the smallest radius at the lower end of the body. It isdesirable that the change in external diameter be gradual and thus.

the infinite number of gradually reducing radii,A

some of which. are indicated by the radii R2, R3

and Ril,v are disposed on an infinite number of center points on theline L between the centerv point'of the largest radius R at the upperend of the whipstock body and the center point of the' smallest radius(not shown) at the extreme lower end of said body. By observing Figures4 to 7 it will be evident that the longitudinal center D of the outersurface of the whipstock body remains in contact with the well borethroughout its entire length so as to form a support which willpreventdisplacement of the whipstock during the,

bore since. there is sufficient clearance" between Y the major portionof. the .,outerf. surface of the whipstock body and the well bore toallow the" elongate body to pass downwardly throughthe irregularities ofa well b'ore. rHowever, because the longitudinal center D of the curvedouter surface of the whipstock body engagesgthe well bore, the functionor eiect, so far as drilling off is concerned, of a' full 'gaugewhipstock is ob.-

tained. p The outer surface of the `whipstock may be formed with aplurality oi ribs 2i which will func-v tionk to resist rotation of thewhipstock duringf the drilling off operation. However, if desired,.-

these ribs may be omitted since they are essential to the invention.

From the foregoing it will be seen that an ini-y proved type ofwhipstock is provided.y The par-` ticular construction permits the useof asubstantially full gauge drill bit, whereby the offset bore which isdrilled is suiiiciently close to the original bore yB that no reamingoperationis necessary;A The whipstock functions as a full gaugewhipstock but'because of the progressively diminish-` ing radius oftheouter surface of the whipstoclrA body toward its lower end, a suioientclearance between said body and the well bore is providedl to allow afree lowering of the whipstock through the bore. The construction issuch that the longi-V not:

as shown inv Figure 4, is substantially concentric to the inner tudinalcentral portion of the. outer surface.y oi.

`the whipstock. indicated. at D is constantv engagement with the wellbore, whereby when the drill is guided' outwardly by the inclined guideface l'9 the whipstock will not be displaced out of position. Theparticular construction. also allows the inclined guide face i to have aconstant radius throughout its length with the inclination of. the facebeing a. predetermined number of degrees per foot in accordance with.the required: angle.

` The openingY I.2 in the collar il. is offsetVV outof alignment withthe center of the collar., said olfset being in a direction away fromthe straight wall section ll of the whipst'ock body. This allows amaximum size bit to be employed since it increases the shoulder i3aformed between the openingV l2' andtheinner Wall lll of; the section ll.g In use, the whipstock is lowered in the usual Inanner bynreans of thedrill. bit and isset in the desired. position. The weight. of theY drillpipe is then imposed upon the shear pin Ib to' fracture the same and.permit downward. movement of the bit along the guide face of thewhipstock. It is noted that the straight wall section il of theWhipstock body facilitates the shearing or fracturing of the pin sinceit allows the bit to move' straight downwardly for a distance beforeengagng. the inclined surface. This4 obviates any possibility of the.bit becoming wedged against the well bore during the shearing operation.After drilling is complete the bit and drill pipe are lifted andobviously the whipstock will beV withdrawn therewith.

. The device is exceptionally simple in construction and provides adistinct' advantage over whipstockswhich have been in general use andwhich, ashas been pointed out, have the outerv surface of their bodyportion on a constant radius throughout its length so that such outerportion is concentric to the inner wall of the well bore; The advantagesof the present invention are accomplished through the particulararrangement of the progressively diminishing radius toward itslower endof the outer. surface o the body portion A oi said whipstock.

, The foregoing description of. the invention is explanatory thereof andvarious changes in the size, shape and materials, as well as inthedetails of the illustrated construction may be made, within thev scopeof the appended clairns, without departing from the` spirit of theinvention.

What I claim and desire to secure by Letters Patentis:

l. A whipstock including, an elongate wedgeshaped body which isgenerally' arcuate in crosssecton, a collar secured to the upper end ofthe body, a drill pipe slidable through the collar, a drill. bit mountedon the lower end. of the drill pipe below the collar and having adiameter at least .equal to the distance between the inner wall. of theupper end of the whipstock' body and the wall of the well bore, thewedge-shaped body having an inclined guide face for guiding. the

bit outwardly into the formation and the outerY located in alongitudinal plane which intersects the longitudinal center of the bodyand the center of the curvature on the outer surface of said.

body, th e center or the curvature being so disposed with respect to thelongitudinal center line or axis of the body and its collar that thelongie tudinal central portion of thecurved outer surface is spaced thesame distance from the center line or axis of the body and collarthroughout the entire length of the body.

2; A whpstock including, an elongate wedgeshaped body which is generallyarcuate in crosssection,` a collar secured to the upper end of the body,a drill pipe slidable through the collar,l a drill bit mounted on thelower end of. the drill'A pipe below the collar and having a diameterat; leastequal to the distance between the inner wall of the upper endof the whipstock, body andthe wall of` the well bore, said whipstockbody having an elongate inclined guide face which is disposed. at anangle with respect tothe longitudinal center line or. axis of the bodyand the collar at the upper end thereof, and the outer curved surface ofsaid body being formed on radii at planes. spaced vertically from eachother along the longitudinal axis of the body from top to bottomtherefof, said radii progressively decreasing toward the. lower end of thebody, the center points of the progressively decreasing radii beinglocated in a. longitudinal plane which intersects the longitudl nalcenter of the body and the center of the curvature on the outer surfaceof said body, the.

center of the curvature being so disposed with respect to thelongitudinal center liney or axis of the body and its collar that thelongitudinal' c entral portion of the curved outer surface. is spacedthe. same distance from. the center line. or. axis of the body andcollar throughout the entire length'. of the body.

3. A whipstock including, an elongate body which isgenerally arcuate incross-section, a collar secured to the upper end of the body,` astraight wall section arcuate in the cross-section immediately below thecollar at the upper endoiv the body, that portion of the body below saidstraight section being Wedge-shaped with an inclined guide surfaceextending longitudinally along one side thereof, the outer surface. ofthe wedge-shaped portionbeing curved with said curvature being formed onradii at planes spaced vertically from each other along the longitudinalaxis of the body from` top to bottom thereof, said'l radii progressivelydecreasing toward the lower end of the body, the center points of theprogressively decreasing radii being located in a longitudinal planewhich intersects the longitudinal center of the. body and the center ofthe curva-- ture on the outer surface of said body, the center of thecurvature being so disposed. withrespect to the longitudinal center lineor axis of the body and its collar that the longitudinal central portionof the curved outer surfaceis spaced the same distance. from the centerline or axis. of the body and collar throughout the entire length of thebody.

4.y A whipstock as set forth in claim 3,. where.- in an opening extendsAthrough the collar and is offset with respect to the center of said.collar.

5. A whipstock including, an elongate body which is generally arcuate incross-section, a col-9.` lar secured to the upper end of the body, astraight wall section arcuate inthe cross-section immediately below thecollar at the upper endof the body, that portion of the body below .saidstraight section being wedge-shaped with an inclined guide surfaceextending longitudinally along one side thereof, the outer surface ofthe wedge-shaped portion being curved with. said curvature being formed.on radii which progres? 9 sively decrease toward the lower end of thebody, the center points of the progressively decreasing radii beinglocated on transverse planes spaced vertically from each other along thelongitudinal axis of the body from top to bottom thereof and also beinglocated along a longitudinal plane which intersects the longitudinalaxis of the body and the center of the curvature on the outer surface ofthe body, with said center points of the decreasing radii being disposedin spaced relationship to each other outwardly from the center of thebody and with the center point for the smallest radius being farthestfrom the axis of thebody, the distance between the center of thecurvature on the outer surface of the body and 15 2,334,747

the longitudinal axis of the body remaining constant throughout thelength of the body.L

f RALPH BUTTOLPH.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS 10 Number Name Date 973,537 Miller Oct. 25, 19101,625,600 Getty Apr. 19, 1927 1,970,761 McVicar Aug. 2l, 1934 2,065,896Keever Dec. 29, 1936 Brantly Nov. 23, 1943

